Filthies

When the first king rose to power, all minors and poors were considered Filthies. It was a simple way of talking about them, as they lived in the mines, among the dirt and the dust.   After the dwarves almost went extinct though, it became an actual social class, and was extended to the dishonored, cast out dwarves. Instead of being executed, the defeated and criminals are thrown into the dwarves sub-city, so that the species still survives.   They are stripped from their names, titles and possessions, and become slaves to the other dwarves. Children of two filthies inherit their parents' status with no hope of redemption, and children of only one filthy with a clan member get the right of being integrated into the clan.   Dwarves who are born and spend their lives in the sub-city tend to get a clearer skin tone than other dwarves.